The present invention relates to a disk wheel of a rotor of a turbomachine such as in particular a turbine or compressor.
In particular, the present invention relates to a disk wheel of the type comprising a series of blades made integral with a central ring.
The disk wheel is fitted together with others of the same type on a shaft of a turbomachine in order to obtain a rotor.
Each disk wheel is then heated and inserted on the shaft so that, after cooling, it remains forced on the shaft itself by interference.
When operating on the blades of each disk wheel, stress is created, which is transmitted by friction to the shaft through the central portion.
In order to increase safety and also the possibility of transmitting high rotation rates to the shaft, grooves for corresponding flaps or keys are normally produced in the internal surface of the central annular portion, in order to fix the disk wheel in position more firmly with respect to the shaft.
This however leads to the disadvantage that under particular operating conditions such as in the presence of corrosive gases for example, an intensification of the stress is created in correspondence with the seats for the flaps, which is further increased by corrosion phenomena.
In other words, corrosion under stress is caused, which is intensified in correspondence with each seat of each key.
With time, this causes breakages, frequently unexpected, as the fractures propagate very rapidly as a result of the corrosive agents.
This consequently jeopardizes the reliability of the rotor and whole turbomachine.